1. Field of the Invention
The present invention relates to a charging generator for a vehicle. More particularly, it relates to construction for cooling the front side of a charging generator for a vehicle.
2. Description of Prior Art
A typical construction for cooling the front side of a charging generator is conventionally that cooling air sucked through a suction window formed at the outer side of a front bearing is discharged from a discharge window formed at the outer circumferential part of a front bracket, while it cools the front bearing, the front side surface of a rotor and a portion of a coil facing the front side of a stator.
The conventional construction of the charging generator will be described in more detail with reference to FIG. 2.
In FIG. 2, a rear bracket 1 and a front bracket 4 are fastened with each other so as to form an outer casing of a charging generator. A rotary shaft 7 is rotatably supported by the front and rear brackets 4, 1 through the respective bearings 8, 5. A rotor 2 is fixedly mounted on the rotary shaft 7 so as to be rotatable therewith. A fan 2a is attached to the rotor 2 at the side of the rear bracket 1, and a fan 2b is attached to the rotor at the side of the front bracket 4 with some space 4d inside of it. A stator 3 is fixedly attached on the inner wall of the front bracket 4 in the vicinity of the joining portion of the front and rear brackets. A coil is wound on the stator 3. A reference numeral 3a designates a portion of the coil projecting to the rear bracket side, and a numeral 3b designates a portion of the coil projecting to the front bracket side. The rear bracket 1 is provided with air intake windows 1a at positions neighboring the bearing 8 and at least one air discharge window 1b at the circumferential portion of the rear bracket 1. The front bracket 4 is provided with at least one air discharge window 4b near the stator 3. A reference numeral 2c designates a space formed in the rotor 2.
In the conventional charging generator having the above-mentioned construction, cooling air sucked through the air intake windows 1a of the rear bracket 1 is passed into the front bracket to cool the rear side of the coil 3a by means of the rear side fan 2a and is discharged outside from the air discharge window 1b. In this case, a part of the cooling air is forced to pass through the space 2c of the rotor 2 by means of the front side fan 2b and is discharged outside from the air discharge window 4b of the front bracket 4, while the cooling air cools the front side of the coil 3b.
In the conventional charging generator, however, sufficient cooling effect can not be expected since the air to be fed to the front bracket side to cool the front side coil 3b is heated in the rear side space thereby becoming warm air, and there is stagnation of air in the space 4d in the front bracket 4. Particularly, there is remarkable increase in temperature in the front bearing 5, whereby the life time and the output performance of the charging generator are decreased.